We propose acquisition of a Hitachi H-7000 transmission electron microscope (TEM). Due to efficiencies in this state-of-the-art instrument system, it will replace two TEM's in the SIUSM EM Facility which are 12 and 15 years old. The TEM instrument system will be used by 7 NIH support investigators and provide opportunities for non-funded investigators to generate preliminary results for subsequent NIH application. Brewer will the new instrument for four projects: 1) to localize the binding site of an undeca-gold-labeled antibody that blocks transjunctional membrane conductance in lens membranes, 2) to quantitate the morphology of cytoplasmic vesicles in E. coli which are produce by cloned genes, 3) to describe the development of synapses in culture hippocampal neurons and 4) to detect paired helical filaments and aluminum toxicity in cultured neurons treated with serum from Alzheimer patients. Caspary will examine the age-related loss of hearing by analysis of the age-related loss of GABA-immunoreactive neurons in the superior olivary complex, the cochlear nucleus and the inferior colliculus. Cooper will study specific surface antigens of the STD pathogens Clamydia trachomatis and Neisseria gonorrhoeae and their interactions with human fallopian tube mucosa in organ culture. Lee will determine the transmitter content in sympathetic nerve terminals of cerebral blood vessels. Rybak will use morphometric to determine their effects on transmembrane ion distributions. Tewari will use the Hitachi H-7000 to examine the interactions of Histoplasma capsulatum with immune and non-immune lymphoid cells and human endothelial cells in culture. Walsh will continue to correlate synaptic morphology with auditory function during development of the cochlear nucleus. Amankwah will extend his previous studies on chronic maternal insults to the fetus in utero to the effects of maternal stress on morphological characteristics of fetal sciatic nerve. To continue to be on the forefront of morphological investigation, this substantial user group needs the efficiencies of a state-of-the-art electron microscope.